Re: Economizer circuit

[Rich Rudman <rmanzan@tscnet.com>]

Michael Bearden wrote:
> 
> OK, I bought a contactor(Kilovac)which says (on the case) 'Requires
> economizer circuit"...Is this the "snubber" which I have seen discussed,
> or a different animal altogether?
> Michael B.


Note to all , and speaking of economiser circuits.
	Painfull EV experience found at the DCP testing Labs.... Read Damon's
RX7

First The KiloVac "Bubba" contactors that most of us kilo amp suckers
use for reactor scramming control.... comes with a ecomiser coil power
reduction circuit. They are the premium part. I forget the exact numbers
but it cuts the coil drive power by about 1/4 once the coil is yanked
in. Cool idea and expected on a $400 range contactor.
	Cut to one batch of ornery T-Rex 1000 amp controllers and 336 volts of
Hawkers. Jeff Bradley, the other partner with Damon and I, has the fun
task of power testing EVERY high voltage controller that leaves this
place IN the RX7 at full power with gravel flying and smoking tires...
This is after the 200Kw coffee perculator test that Damon does on the
test bench.  The orneryness was a full controller shut down and stall
just as you floored the Rex. Jeff pulled and replaced the controllers
(like 6 of them) about 20 times in one day for Damon to try another
trick.  The Demented one had a good frown buidt up. Jeff had the
controller mount/remove down to about 3 Minutes flat, with lots of
practice. I was staying out of the way in the AC lab. We all were
certain that we had a bad bug inside the Rexs...but just could not
actually find it. Bummer kinda thing that all you EE types are famillure
with. with 1200 amp pulses blasting about at 18Khz... noise is gonna
happen. 
	The conflicting item is the T2K 2000 plus amp controller permanatley
mounted in the same car had no such problems, Instant vaprization of
rubber and sliky smooth from creap mode to tire fry mode. So it really
looked like a problem inside the new Rexs. This evil irritation went on
for a few days to weeks. Some controllers would some wouldn't. 
	The solutions was evident when Damon came out of the Car side of the
shop cussing up a storm.  The Bubba was mounted about 6 inches away from
the "Temp" controller bolts, exactly in line with the main Motor loop
buss bar...but on the Fan end of the controller. The magnetic fields
here are pretty intense with the full motor loop current making a about
3/4 of a turn inside the controller. That's 900 amp turns of magnetic
energy being created...about 6 inches from the "Economiser" circuit of
the Bubba. A tattle tail LED on the Controller to contactor coil drive
line, never Blinked... but the contactor dropped out anyways.  Glitch
found.....outside of DCP desinged hardware. Grrrrrrr!!!  The T2K is
about 24 iches farther away from the Contactor, with no problems.
	So the warning is... Mount your Bubba contactor or any other field
sensitive equipment... at least a foot or more way from the Back end of
our Kilo amp monsters. Certain makes of cooling fans Die inside the
controllers also. We have had to select our cooling fans so this is not
a problem when you need the cool wind the most.
	Ain't high power electronics fun!!!!

Rich Rudman
DCP Inc.
-- 
http://www.manzanitamicro.com